Optical glass

Abstract

Provided is an optical glass excellent in radiation resistance and moldability.　This optical glass has an SiO2 content of 45.00-66.00 mass%, an Al2O3 content of 3.00-10.00 mass%, a total content of Li2O, Na2O, and K2O of 15.00-30.00 mass%, a CeO2 content of 1.90-8.00 mass%, and an Fe2O3 content of less than 0.010 mass%.

Description

Optical glass

[0001] The present invention relates to optical glass.

[0002] Optical glass is used in devices having an optical system and the like. More specifically, optical glass is used as a material for lenses, prisms, and the like. As optical glass, glass containing cerium oxide (CeO ２ ) is also known. For example, in Patent Document 1, glass containing 0.3 to 10.0% by mass of CeO ２ is disclosed.

[0003] International Publication No. 2024 / 203958

[0004] In optical glass, it may be required to have excellent resistance to radiation (radiation resistance). In addition, it is desirable that optical glass has high formability, that is, it is easy to be processed into a desired shape in order to realize a desired optical function. When the present inventors examined the glass described in the above patent document, it sometimes did not satisfy the radiation resistance and formability required recently.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an optical glass having excellent radiation resistance and formability.

[0006] As a result of intensive studies on the above problems, the present inventors have found that an optical glass having excellent radiation resistance and formability can be obtained by setting a predetermined composition, and have completed the present invention.

[0007] That is, the present inventors have found that the above problems can be solved by the following configuration. [1] The content of SiO ２ is 45.00 to 66.00% by mass, the content of Al ２ O ３ is 3.00 to 10.00% by mass, the total content of Li ２ O, Na ２ [[ID=3�]] O and K ２ O is 15.00 to 30.00% by mass, the content of CeO ２ is 1.90 to 8.00% by mass, and the content of Fe ２ O ３[2] Optical glass having a content of less than 0.010% by mass. [1] The optical glass according to [1], further containing at least one component selected from the group consisting of MgO, CaO, SrO, and BaO, wherein the total content of MgO, CaO, SrO, and BaO is 5.00 to 30.00% by mass. [3] β-OH value of 1.00 mm －１ The optical glass described in [1] or [2] below. [4] The optical glass described in any one of [1] to [3], having a bending point of 630°C or less. [5] The optical glass described in any one of [1] to [4], having a maximum thickness of 0.3 mm or more. [6] The optical glass described in any one of [1] to [5], having a transmittance of 80.00% or more at a wavelength of 800 nm with a plate thickness of 5 mm. [7] The optical glass described in any one of [1] to [6], having a transmittance of 80.00% or more at a wavelength of 1300 nm with a plate thickness of 5 mm. [8] The optical glass described in any one of [1] to [7], having a lens-like shape. [9] The optical glass described in any one of [1] to [8], used as a lens for optical communication.

[10] The optical glass described in any one of [1] to [8], used for space applications.

[11] Optical glass described in any one of [1] to [7], used for radiation shielding purposes.

[0008] According to the present invention, optical glass with excellent radiation resistance and moldability can be provided.

[0009] The present invention will now be described in detail. The following descriptions of constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0010] In this specification, numerical ranges expressed using "~" mean a range that includes the values ​​written before and after "~" as the lower and upper limits. In numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Also, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this specification, the content of each component of optical glass is expressed as a mass percentage on an oxide basis unless otherwise specified. That is, in this specification, the content of each component of optical glass is expressed as a mass percentage on an oxide basis relative to the total content of each component on an oxide basis unless otherwise specified. In the composition of optical glass, "substantially not contained" means not contained except for unavoidable impurities contained in the raw materials, etc., i.e., not intentionally included. Specifically, for components other than those described as part of the glass composition, for example, less than 0.1% is preferred, 0.08% or less is more preferred, and 0.05% or less is even more preferred. In this specification, each element is represented by its respective element symbol.

[0011] <Optical Glass> The optical glass of the present invention is made of SiO ２ The content is 45.00 to 66.00% by mass, Al ２ O ３ The content is 3.00 to 10.00 mass%, and Li ２ O, Na ２ O and K ２ The total O content is 15.00 to 30.00 mass%, and CeO ２ The content is 1.90 to 8.00% by mass, and Fe ２ O ３ The content is less than 0.010% by mass.

[0012] The mechanism by which the optical glass of the present invention exhibits excellent radiation resistance and moldability is not entirely clear, but the inventors speculate as follows: The optical glass of the present invention is CeO ２If the content of is within the above range, discoloration can be suppressed even when ionizing radiation (e.g., X-rays, gamma rays, electron beams, proton beams, etc.) is irradiated onto the optical glass. In addition, the optical glass of the present invention contains Fe ２ O ３ When the content of is within the above range, discoloration can be suppressed and the transmittance does not decrease easily even when the optical glass is irradiated with ionizing radiation, etc. Furthermore, the optical glass of the present invention is SiO ２ The content of, and Li ２ O, Na ２ O and K ２ Because the total oxygen content is within the predetermined range, the temperature at which the optical glass can be molded is easily reduced, resulting in excellent moldability. Therefore, the optical glass of the present invention is considered to have excellent radiation resistance and moldability.

[0013] The optical glass of the present invention will be described in detail below. As mentioned above, unless otherwise specified, the content of each component of the optical glass is expressed as a mass percentage based on the oxide.

[0014] [Composition] In the optical glass of the present invention, SiO ２ The content is 45.00 to 66.00%. SiO ２ It is a component that forms the glass skeleton. It is also a component that easily improves the chemical durability of optical glass. In the above respect, SiO ２ The content of SiO is preferably 50.00% or more, more preferably 51.00% or more, even more preferably 52.00% or more, particularly preferably 53.00% or more, and in that order, preferably 54.00% or more, 55.00% or more, 56.00% or more, 57.00% or more, 58.00% or more, 59.00% or more, and 60.00% or more. ２ The content of is preferably 65.80% or less, more preferably 65.60% or less, even more preferably 65.40% or less, and particularly preferably 65.20% or less, in that order, 65.00% or less, 64.80% or less, 64.60% or less, 64.40% or less, 64.20% or less, and 64.00% or less. Furthermore, lowering the high-temperature viscosity makes it easier to manufacture larger optical glass.

[0015] In the optical glass of the present invention, Al ２ O ３ The content is 3.00 to 10.00%. ２ O ３ Al is a component that improves the mechanical properties (Young's modulus and fracture toughness, etc.) of optical glass and easily enhances its chemical durability. Improved chemical durability makes it easier to prevent discoloration of optical glass. Furthermore, it is a component that facilitates ion exchange during chemical strengthening of optical glass. In the above respects, Al ２ O ３ The content of Al is preferably 3.20% or more, more preferably 3.40% or more, even more preferably 3.60% or more, particularly preferably 3.80% or more, and in that order, preferably 4.00% or more, 4.20% or more, and 4.40% or more. ２ O ３ The content of is preferably 8.00% or less, more preferably 7.50% or less, more preferably 7.00% or less, more preferably 6.50% or less, more preferably 6.00% or less, and even more preferably 5.50% or less, from the standpoint of reducing devitrification, further improving lens moldability, and further lowering high-temperature viscosity. Furthermore, lowering high-temperature viscosity makes it easier to manufacture larger optical glass.

[0016] In the optical glass of the present invention, Li ２ O, Na ２ O and K ２ The total O content is 15.00 to 30.00%. That is, the optical glass of the present invention is Li ２ O, Na ２ O and K ２ It contains at least one component selected from the group consisting of O. ２ O, Na ２ O and K ２ O makes it easier to lower the bending point of optical glass and improve moldability. In the above respect, Li ２ O, Na ２ O and K ２The total O content is preferably 15.20% or more, more preferably 15.40% or more, even more preferably 15.60% or more, particularly preferably 15.80% or more, and in that order, preferably 16.00% or more, 16.20% or more, 16.40% or more, 16.60% or more, 16.80% or more, and 17.00% or more. ２ O, Na ２ O and K ２ The total O content is preferably 27.00% or less, more preferably 24.00% or less, and even more preferably 21.00% or less, in terms of further improving weather resistance.

[0017] Li ２ O is a component that can improve the mechanical properties of optical glass (such as Young's modulus and fracture toughness) and form a surface compressive stress layer in optical glass by ion exchange, and may be included. ２ If O is included, Li ２ The O content is preferably 0.10% or more, more preferably 0.50% or more, and even more preferably 1.00% or more. ２ The O content is 30.00% or less, preferably 25.00% or less, and more preferably 20.00% or less. The optical glass of the present invention is Li ２ It is not necessary to substantially include O.

[0018] Na ２ O is a component that can form a surface compressive stress layer in optical glass by ion exchange, and may be included. The optical glass of the present invention is Na ２ If O is included, Na ２ The O content is preferably 5.00% or more, more preferably 10.00% or more, and even more preferably 15.00% or more. ２ The O content is 30.00% or less, preferably 27.00% or less, more preferably 24.00% or less, and even more preferably 21.00% or less.

[0019] K ２ O is a component that can increase the ion exchange rate and may be included. The optical glass of the present invention is K ２ If O is included, K ２The O content is preferably 0.10% or more, more preferably 0.15% or more, even more preferably 0.20% or more, and particularly preferably 0.21% or more. ２ The O content is 30.00% or less, preferably 10.00% or less, more preferably 5.00% or less, and even more preferably 2.00% or less.

[0020] In the optical glass of the present invention, CeO ２ The content is 1.90-8.00%. CeO ２ It is a component that improves the radiation resistance of optical glass. Also, CeO ２ It is an ingredient that has the effect of blocking ultraviolet rays. In the above respect, CeO ２ The content is preferably 2.00% or more, more preferably 2.10% or more, even more preferably 2.20% or more, particularly preferably 2.30% or more, and in that order, preferably 2.40% or more and 2.50% or more. ２ The content of is preferably 7.00% or less, more preferably 6.00% or less, even more preferably 5.00% or less, particularly preferably 4.00% or less, and in order thereafter, 3.80% or less, 3.60% or less, and 3.40% or less are preferred in terms of reducing devitrification.

[0021] In the optical glass of the present invention, Fe ２ O ３ The content is less than 0.010%. Fe ２ O ３ The content of is preferably 0.009% or less, preferably 0.008% or less, preferably 0.007% or less, preferably 0.006% or less, and more preferably 0.005% or less. In the optical glass of the present invention, Fe ２ O ３ It is also preferable that it is not included. ２ O ３ "Not containing" means that, in the measurement method described later, it is below the detection limit.

[0022] The optical glass of the present invention may contain other components. Other components that the optical glass of the present invention may contain are described below.

[0023] The optical glass of the present invention preferably contains at least one component selected from the group consisting of MgO, CaO, SrO, and BaO. In particular, the total content of MgO, CaO, SrO, and BaO is preferably 5.00% or more, more preferably 7.00% or more, and even more preferably 10.00% or more, in terms of lowering the bending point of the optical glass and further improving its moldability. Furthermore, the total content of MgO, CaO, SrO, and BaO is preferably 30.00% or less, more preferably 20.00% or less, and even more preferably 15.00% or less. It is also preferable that the optical glass of the present invention contains MgO and CaO. Furthermore, it is also preferable that the optical glass of the present invention contains MgO and CaO, and that the total content of MgO and CaO is within the above preferred range.

[0024] When the optical glass of the present invention contains MgO, the MgO content is preferably 0.50% or more, more preferably 1.00% or more, and even more preferably 2.00% or more. Furthermore, the MgO content is preferably 20.00% or less, more preferably 15.00% or less, even more preferably 10.00% or less, particularly preferably 8.00% or less, and then, in order, preferably 6.00% or less, 5.00% or less, and 4.50% or less.

[0025] When the optical glass of the present invention contains CaO, the CaO content is preferably 1.00% or more, more preferably 2.00% or more, and even more preferably 4.00% or more. Furthermore, the CaO content is preferably 25.00% or less, more preferably 20.00% or less, even more preferably 15.00% or less, particularly preferably 12.00% or less, and so on, with 10.00% or less, 9.00% or less, and 8.00% or less being preferred in that order.

[0026] If the optical glass of the present invention contains SrO, the SrO content is preferably 1.00% or less, more preferably 0.50% or less, and even more preferably 0.10% or less. It is also preferable that the optical glass of the present invention is substantially SrO-free.

[0027] When the optical glass of the present invention contains BaO, the content of BaO is preferably 1.00% or less, more preferably 0.50% or less, and even more preferably 0.10% or less. In addition, it is also preferable that the optical glass of the present invention substantially does not contain BaO.

[0028] The optical glass of the present invention may contain B ２ O ３ . B ２ O ３ can improve the mechanical properties of the optical glass. The content of B ２ O ３ is preferably 9.00% or less, more preferably 8.00% or less, even more preferably 7.00% or less, particularly preferably 6.00% or less, and in order, 5.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less is preferable in terms of facilitating the improvement of the mechanical strength of the optical glass, further improving the acid resistance, and suppressing the occurrence of phase separation during production. In addition, it is also preferable that the optical glass of the present invention substantially does not contain B ２ O ３ .

[0029] The optical glass of the present invention may contain TiO ２ . TiO ２ can suppress solarization (coloring) by ultraviolet rays (especially UVC with a wavelength of 100 to 280 nm). The content of TiO ２ is preferably 0.001% or more in terms of obtaining the above effects. The content of TiO ２ is preferably 1.00% or less, more preferably 0.50% or less, even more preferably 0.10% or less, and particularly preferably 0.01% or less in terms of suppressing the coloring of the optical glass. In addition, it is also preferable that the optical glass of the present invention substantially does not contain TiO ２ .

[0030] The optical glass of the present invention may contain ZrO ２ . ZrO ２ can reduce the viscosity of the optical glass at high temperatures. The content of ZrO ２ is preferably 5.00% or less, more preferably 2.00% or less, and even more preferably 1.00% or less. In addition, the optical glass of the present invention preferably substantially does not contain ZrO２ It is also preferable that it substantially does not include it.

[0031] The optical glass of the present invention may contain ZnO. ZnO can improve the meltability of the optical glass at high temperatures. The ZnO content is preferably 1.00% or less, more preferably 0.50% or less, and even more preferably 0.25% or less, in order to suppress the occurrence of defects in the optical glass. It is also preferable that the optical glass of the present invention is substantially free of ZnO.

[0032] The optical glass of the present invention further suppresses the decrease in transmittance, V ２ O ５、 Cr ２ O ３ CoO, MnO ２ Preferably, it contains substantially no [the specified element].

[0033] The optical glass of the present invention may contain a clarifying agent. The clarifying agent may be SO ３ Examples include chlorides and fluorides.

[0034] The optical glass of the present invention uses an antimony compound (e.g., Sb) as a clarifying agent and redox agent. ２ O ３ ) may contain. The antimony compound content is preferably 0.5% or less, more preferably 0.2% or less, 0.1% or less, 0.08% or less, 0.05% or less, and 0.01% or less. On the other hand, antimony-based clarifying agents tend to change the oxidation-reduction atmosphere during the melting process, and the valence distribution of Ce (Ce ３＋ / Ce ４＋ Because this can destabilize the control of certain substances and make it difficult to control product characteristics such as transmittance and radiation resistance, it is most preferable to substantially omit them.

[0035] The content of each component in the optical glass of the present invention is analyzed by the non-standard FP method using a wavelength-dispersive X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku Corporation).

[0036] [Physical Properties] The physical properties of the optical glass of the present invention will be described below.

[0037] The refractive index n of the optical glass of the present invention ｄ A refractive index n of the optical glass of the present invention is preferable in terms of miniaturization and thinning of the component obtained by applying optical glass. ｄ In this specification, the refractive index n of the optical glass is preferably 1.65 or less, in that the dispersion does not become too large. ｄ This involves processing a glass sample into a rectangular parallelepiped shape with sides of 20-30 mm and a thickness of 5 mm, and measuring the refractive index in the d-line (wavelength 587.6 nm) using a Carnew precision refractometer (KPR-3000, manufactured by Shimadzu Corporation).

[0038] The Abbe number of the optical glass of the present invention is preferably 40 or more, and more preferably 50 or more. The Abbe number of the optical glass of the present invention is often 70 or less. Note that the above Abbe number (ν ｄ ) is a value calculated by the following formula: ν ｄ = (n ｄ -1) / (n Ｆ -n Ｃ ) In the above formula, each symbol has the following meaning: ・n ｄ : Refractive index in the d-line (wavelength 587.6 nm)・n Ｆ : Refractive index in the F line (wavelength 486.1 nm)・n Ｃ :Refractive index at the C line (wavelength 656.3 nm). Note that the Abbe number is the refractive index n of the optical glass. ｄ It can be measured with a measuring device.

[0039] The density of the optical glass of the present invention is 1.80 g / cm³, which further improves the shielding performance of electron beams. ３ The above is preferable, specifically 2.20 g / cm³. ３ The above is more preferable. Furthermore, the density of the optical glass of the present invention is 3.00 g / cm³ from the viewpoint of reducing the weight of the component obtained by applying the optical glass. ３ The following is preferable: 2.70 g / cm³ ３ The following is more preferable. In this specification, the density of optical glass is measured by the Archimedes method.

[0040] The coefficient of thermal expansion (CTE) of the optical glass of the present invention is 200 × 10⁻¹⁰, which further reduces warping due to heat. －７ ℃ －１ The following is preferable: 190 x 10 －７ ℃ －１ The following is more preferable: 180 x 10 －７ ℃ －１ The following is even more preferable: 170 x 10 －７ ℃ －１ The following are particularly preferred, in the following order: 160 x 10 －７ ℃ －１ Below, 150 x 10 －７ ℃ －１ Below, 140 x 10 －７ ℃ －１ Below, 130 x 10 －７ ℃ －１ Below, 120 x 10 －７ ℃ －１ Below, 110 x 10 －７ ℃ －１ The following is preferable. Furthermore, the CTE of the optical glass of the present invention is 40 × 10 －７ ℃ －１ The above is preferable, 50 x 10 －７ ℃ －１ The above is more preferable, 60 x 10 －７ ℃ －１ The above is even more preferable, 70 x 10 －７ ℃ －１ The above is particularly preferred, 80 x 10 －７ ℃ －１ The above is the most preferred method. In this specification, the CTE of optical glass is measured using a thermomechanical analyzer (Brker, product name: TD5000SA) on a cylindrical sample with a diameter of 5 mm and a height of 20 mm, according to the method specified in JIS R 3102:1995. The heating rate is 5°C / min, and the measurement temperature range is 50 to 350°C.

[0041] The glass transition temperature of the optical glass of the present invention is preferably 600°C or lower, more preferably 560°C or lower, and even more preferably 550°C or lower. The lower limit of the glass transition temperature is not particularly limited, but it is often 300°C or higher. The glass transition temperature is determined by measuring a sample processed into a cylindrical shape with a diameter of 5 mm and a length of 20 mm, according to the method specified in JIS R 3103:2001, using a thermomechanical analyzer (Brker, product name: TD5000SA) at a heating rate of 5°C / min.

[0042] The inflection point of the optical glass of the present invention is preferably 650°C or lower, and more preferably 630°C or lower. The lower limit of the inflection point is not particularly limited, but it is often 400°C or higher. The inflection point refers to the temperature at which the maximum peak is observed when a thermal expansion curve is obtained by measuring in the same manner as the glass transition point.

[0043] The devitrification temperature of the optical glass of the present invention is preferably 1400°C or lower, as this makes it easier to enlarge the optical glass. In this specification, the devitrification temperature of the optical glass is measured, for example, by the following method. First, about 4 g of the optical glass sample is placed on a platinum dish and held in an electric furnace set to the test temperature for 17 hours, after which the sample is removed and rapidly cooled. After the temperature has decreased to room temperature, the presence or absence of devitrification is checked with an optical microscope, and the temperature range in which the presence or absence of devitrification changes by varying the test temperature as described above is investigated. The devitrification temperature is determined by setting the highest temperature at which devitrification was confirmed and the lowest temperature at which devitrification was confirmed in the above procedure as the upper and lower limits. Note that a devitrification temperature of 1400°C or lower means that the upper limit of the devitrification temperature determined by the above method is 1400°C or lower.

[0044] The β-OH value of the optical glass of the present invention is 1.00 mm, which further improves the transmittance of near-infrared light (more specifically, light with wavelengths from 800 nm to 1500 nm). －１ The following is preferable: 0.50 mm －１ The following is more preferable: 0.40 mm －１ The following is even more preferable: 0.30 mm －１ The following is particularly preferred: 0.20 mm －１ The following is most preferable. There is no particular limit to the β-OH value, but 0.01 mm is preferable. －１The above is often the case. The β-OH value is a value obtained by measuring the transmittance of optical glass using an FT-IR (Fourier Transform Infrared Spectroscopy) instrument and using the following formula: (β-OH value) = (1 / X) log １０ (T1 / T2) In the above formula, each symbol has the following meaning: • T1: Reference wavelength 3846 cm －１ Transmittance in (unit: %) • T2: Hydroxyl group absorption wavelength 3400-3800 cm －１ Minimum transmittance in %; X: Thickness of the sample (in mm)

[0045] In the optical glass of the present invention, the transmittance T at a wavelength of 800 nm ８００ The transmittance T is preferably 80.00% or higher, more preferably 82.00% or higher, even more preferably 85.00% or higher, and particularly preferably 90.00% or higher. ８００ When the transmittance T is within the above range, the light transmittance at near-infrared wavelengths is high, which can improve energy efficiency during communication using, for example, near-infrared wavelength lasers. ８００ There is no particular upper limit, but it is often 99.90% or less. Transmittance T ８００ The transmittance is measured using a spectrophotometer (Hitachi High-Tech Corporation, "U-4100"). The sample used for measuring transmittance is an optical glass measuring 20 mm in length, 20 mm in width, and 5 mm in thickness. That is, the above transmittance T ８００ This refers to the transmittance at a wavelength of 800 nm for a sample with a plate thickness of 5 mm.

[0046] In the optical glass of the present invention, the transmittance T at a wavelength of 1300 nm １３００ The transmittance T is preferably 80.00% or higher, more preferably 82.00% or higher, even more preferably 85.00% or higher, and particularly preferably 90.00% or higher. １３００ When the transmittance T is within the above range, the light transmittance at near-infrared wavelengths is high, which can improve energy efficiency during communication using, for example, near-infrared wavelength lasers. １３００ There is no particular upper limit, but it is often 99.90% or less. Transmittance T １３００ The above transmittance T８００ It is measured in the same manner as above. That is, the transmittance T １３００ This refers to the transmittance at a wavelength of 1300 nm for a sample with a plate thickness of 5 mm.

[0047] Furthermore, in optical glass, the transmittance at a wavelength of 1300 nm before the X-ray irradiation test (T above) １３００ ΔT is the value obtained by subtracting the transmittance at a wavelength of 1300 nm after X-ray irradiation from ). １３００ [Xray] is preferably 1.50% or less, more preferably 0.50% or less, and even more preferably 0.30% or less. The above ΔT １３００ [Xray] may be 0.00% or more.

[0048] The above ΔT １３００ The X-ray irradiation test for measuring [Xray] is performed according to the following procedure. A wavelength-dispersive X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku Corporation) is used for X-ray irradiation. An optical glass sample measuring 20 mm in length, 20 mm in width, and 5 mm in thickness is brought into the measurement area of ​​the above apparatus and irradiated with X-rays. Rh is used as the target for the X-ray tube, and the power supplied to the X-ray tube is set to 50 kV-48 mA, 40 kV-60 mA, and 30 kV-80 mA. More specifically, the X-ray irradiation is performed first by irradiating with X-rays for about 3 minutes using an Al25 filter at an input power of 50 kV-48 mA, and then by irradiating with X-rays for about 1 minute using a Ni400 filter at an input power of 50 kV-48 mA. Furthermore, X-rays are irradiated for approximately 30 seconds at an input power of 40kV-60mA using an Al25 filter, and finally, X-rays are irradiated for approximately 3 minutes and 30 seconds at 30kV-80mA without using a filter. After the above X-ray irradiation, the transmittance (T) is measured. １３００ The transmittance at a wavelength of 1300 nm after X-ray irradiation is measured in the same manner as the measurement method, and ΔT １３００ Calculate [Xray].

[0049] The Young's modulus of the optical glass of the present invention is preferably 60 GPa or higher, more preferably 62 GPa or higher, even more preferably 64 GPa or higher, particularly preferably 66 GPa or higher, and in that order, preferably 68 GPa or higher, 70 GPa or higher, and 72 GPa or higher. When the Young's modulus is within the above range, the glass becomes less prone to bending, and its resistance to impact is further improved. Furthermore, the Young's modulus of the optical glass of the present invention is preferably 115 GPa or lower, more preferably 110 GPa or lower, even more preferably 105 GPa or lower, particularly preferably 100 GPa or lower, and in that order, preferably 95 GPa or lower, 90 GPa or lower, and 85 GPa or lower. The Young's modulus of the optical glass of the present invention is measured using an optical glass measuring 30 mm in length, 30 mm in width, and 1 mm in thickness, by the ultrasonic pulse method (JIS R1602:1995).

[0050] [Applications and Shapes] The optical glass of the present invention can be applied to various applications. In particular, because of its excellent radiation resistance, it is useful as optical glass (especially optical glass for optical communication) used in environments exposed to radiation (e.g., space environments, high-altitude environments, near radiation generating equipment). That is, the optical glass of the present invention is preferably used for space applications. In the above optical communication, lasers in the infrared wavelength range may be used, and the optical glass of the present invention is suitable for the above ΔT １３００ Because of its small [Xray] value, it is useful as optical glass for optical communication using infrared light (for example, optical communication lenses). Furthermore, the optical glass of the present invention can also be used for radiation shielding applications. The above-mentioned space applications refer to use in the space environment, and the optical glass of the present invention is preferably used in optical components used in outer space (for example, lenses, prisms, mirrors, filters, diffraction gratings, and windows, etc.).

[0051] The optical glass of the present invention can be processed into various shapes depending on the intended use (e.g., the optical component described above). For example, the optical glass of the present invention can be processed into a lens shape. That is, it is preferable that the optical glass of the present invention be in a lens shape. The processing method is not particularly limited, and known processing methods can be applied. For example, the optical glass of the present invention can be heated to a deformable temperature and deformed into a desired shape. Because the optical glass of the present invention has excellent formability, it is easy to process into a desired shape.

[0052] The shape of the optical glass is not particularly limited, but the maximum thickness of the optical glass of the present invention is preferably 0.3 mm or more, more preferably 0.4 mm or more, even more preferably 0.5 mm or more, particularly preferably 0.6 mm or more, and then preferably 0.8 mm or more, 1.0 mm or more, and 1.5 mm or more, in that order. The maximum thickness of the optical glass of the present invention is not particularly limited, but is often 1 m or less. The maximum thickness of the optical glass is determined as follows. First, the maximum length direction of the optical glass having a predetermined shape is determined. The maximum length direction refers to the direction that shows the longest distance from one surface of the predetermined shape to the other surface of the optical glass having a predetermined shape. Hereinafter, the maximum length direction will also be called the "X-axis direction". Next, the direction that is perpendicular to the X-axis direction and shows the maximum length of the optical glass of the predetermined shape is determined. Hereinafter, the direction that is perpendicular to the X-axis direction and shows the maximum length will also be called the "Y-axis direction". Here, the direction perpendicular to the X-axis direction and the Y-axis direction will be called the Z-axis direction. The maximum thickness of the optical glass is the maximum length of the optical glass of the predetermined shape in the Z-axis direction. For example, if the optical glass has a plano-convex lens shape, where the planar view (shape as seen from the optical axis) is circular, its maximum thickness is the maximum distance from the plane of the plano-convex lens to the convex surface. If the optical glass is in the form of a plate, the plate thickness is the maximum thickness of the optical glass.

[0053] The present invention will be described in more detail below based on the following examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples. Examples 1 to 4 below are examples, and Example 5 is a comparative example.

[0054] <Manufacturing of Optical Glass> First, the raw materials were weighed and mixed so that each component was contained in the proportions shown in the table below (expressed as mass percentage based on oxide). The mixed raw materials were placed in a platinum crucible, heated to 1550°C in an electric furnace to melt, homogenized by stirring with a stirrer, and allowed to stand to remove bubbles to obtain molten glass. The obtained molten glass was poured into a carbon mold, held at 600°C for 1 hour, and then cooled at 1.0°C / min to obtain a glass block of optical glass. The content of each component shown in the table below was measured by the method described above.

[0055] <Measurement and Evaluation of Optical Glass> From the glass block obtained in the above procedure, cut out a sample of a predetermined shape, and measure the refractive index n of the optical glass using the method described above. ｄ The density, thermal expansion coefficient, glass transition temperature, flexion point, Young's modulus, devitrification temperature, and β-OH value were measured. The results are shown in the table below. In addition, the transmittance T at a wavelength of 800 nm was measured using the method described above. ８００ , and the transmittance T at a wavelength of 1300 nm １３００ The transmittance T at a wavelength of 1300 nm after X-ray irradiation was measured using the method described above. １３００ [Xray] was measured to evaluate radiation resistance. Generally, the bending point corresponds to the temperature at which glass begins to deform under its own weight. Therefore, a low bending point indicates that molding is possible at a lower temperature, resulting in excellent processability.

[0056] <Results> The composition of the optical glass for each example, as well as the measurement and evaluation results described above, are shown in Table 1 below. Note that in Table 1, "R ２ The "O" column is Li ２ O, Na ２ O and K ２This shows the total content of O. The "RO" column shows the total content of MgO, CaO, SrO, and BaO. In Table 1, "ΔT" １３００ In the column labeled "T", the value is obtained by subtracting the transmittance at a wavelength of 1300 nm after X-ray irradiation from the transmittance at a wavelength of 1300 nm before X-ray irradiation. １３００ Enter the [Xray].

[0057]

[0058] As shown in Table 1, the optical glass of the present invention (Examples 1 to 4) was found to have a lower bending point and superior moldability compared to the optical glass of Example 5. Furthermore, the optical glass of the present invention (Examples 1 to 4) showed a lower change in transmittance (ΔT) before and after X-ray irradiation compared to the optical glass of Example 5. １３００ It was confirmed that the X-ray size is small and that it has excellent radiation resistance.

[0059] Furthermore, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2025-009053, filed on January 22, 2025, and the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2025-053465, filed on March 27, 2025, are incorporated herein by reference as disclosure of the present invention.

Claims

1. The content of SiO ３ , ２ is 45.00 to 66.00% by mass, and the content of Al ２ O ３ is 3.00 to 10.00% by mass, and the total content of Li ２ O, Na ２ O and K ２ O is 15.00 to 30.00% by mass, and the content of CeO ２ is 1.90 to 8.00% by mass, and the content of Fe ２ O ３ is less than 0.010% by mass, an optical glass.

2. The optical glass according to claim 1, further containing at least one component selected from the group consisting of MgO, CaO, SrO, and BaO, wherein the total content of MgO, CaO, SrO, and BaO is 5.00 to 30.00% by mass.

3. β-OH value is 1.00 mm －１ The optical glass according to claim 1 or 2, which is as follows:

4. The optical glass according to claim 1 or 2, wherein the bending point is 630°C or lower.

5. The optical glass according to claim 1 or 2, wherein the maximum thickness is 0.3 mm or more.

6. The optical glass according to claim 1 or 2, wherein the transmittance at a wavelength of 800 nm is 80.00% or more at a plate thickness of 5 mm.

7. The optical glass according to claim 1 or 2, wherein the transmittance at a wavelength of 1300 nm is 80.00% or more at a plate thickness of 5 mm.

8. The optical glass according to claim 1 or 2, having a lens-like shape.

9. The optical glass according to claim 1 or 2, used in lenses for optical communications.

10. The optical glass according to claim 1 or 2, for use in space applications.

11. The optical glass according to claim 1 or 2, used for radiation shielding purposes.

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